docs: def prep_folder(self, seq):
          """Take in a sequence string and prepares the folder for the I-TASSER run."""
          itasser_dir = op.join(self.root_dir, self.id)
  
          if not op.exists(itasser_dir):
              os.makedirs(itasser_dir)
  
          tmp = {self.id: seq}
  
          fasta.write_fasta_file_from_dict(indict=tmp,
                                           outname='seq',
                                           outext='.fasta',
                                           outdir=itasser_dir)
          return itasser_dir